Wayland: Dragging and dropping files into other programs only works the second time you hover over them

[InmanInman]

Steps to reproduce:

1. drag a file from caja to a non-mate application e.g. kate or firefox with a website supporting drag and drop (it seems to work with mate applications, or at least with pluma first try)

2. your mouse will show the red crossed out icon and it won't work

3. drag the file off the application, and back onto the application

4. now it works

it would be better if it just worked the first time

[lukefromdc]

I was just unable to duplicate this dragging a file from caja to firefox in the wayland session. What GTK and GLIB versions are you using, and what video driver? The latter may potentially effect compositor behavior though I really don't know. Last round of DnD bugs turned out to be a GTK issue

[InmanInman]

I'm on kubuntu 25.04, using plasma under wayland, but with caja as the file manager.

glib version appears to be 2.84.1-1ubuntu0.1

gtk is 3.24.49-2ubuntu1
and 4.18.5+ds-0ubuntu0.1

the video driver is intel:

00:02.0 VGA compatible controller: Intel Corporation Alder Lake-S GT1 [UHD Graphics 730] (rev 0c)

e: can you try maybe using kate instead of firefox? I think firefox has both a gtk and qt frontend IIRC, maybe it's specific to dragging into qt apps, since I don't get the problem with pluma

[lukefromdc]

Since I've never seen this in wayfire, you might have a Plasma issue. Way to find out (if you can) is to install wayfire (with or without the MATE wayland session) and repeat the test with caja and firefox (or whatever) running under wayfire. If the problem is gone you have a plasma bug, if still present most likely GTK but GLIB also possible. I've got glib 2.83.4 so I will have to update that anyway, if this problem then appears that's the culprit. Out of time at the moment, will have to test later.

[InmanInman]

Hm, I'm sorry, but I'm not sure how to test it. On its own, Wayfire just brings up a black screen with a cursor. And MATE seems to still use X11 on kubuntu 25.04.

[lukefromdc]

MATE will default to x11 for quite some time. The main reason for the wayland port is as a precaution against distros dropping x11 entirely. The wayland session is considered experimental at this time but mostly works. I myself don't know much about the internal mechanics of drag and drop.